心肌缺血再灌注亚细胞钙变化电镜细胞化学研究

The Electron Microscopic Cytochcmlcal Study of Subcellular Ca(2+) Alterations during Ischcmia and Rcperfusion in Isolatcd Rat Ventricular Myocytes

应用Ｃａ（２＋）细胞化学探针－焦锑酸钾技术，结合ｘ线电子探针微区分析研究心肌缺血再灌注肌浆网、线粒体等亚细胞Ｃａ（２＋）原位分布变化。结果表明，正常细胞Ｃａ（＠＋）主要位于肌浆网内、细胞膜及细胞核内，胞浆及线粒体内无Ｃａ（２＋）颗粒。缺血３０ｍｉｎ，Ｃａ（２＋）分布变化不明显。再灌注３０ｍｉｎ及６０ｍｉｎ肌浆网及肌膜Ｃａ（２＋）明显减少，同时胞浆及线粒体内出现大量Ｃａ（２＋）沉淀颗粒。Ｘ线电子探针微区分析证实心肌亚细胞高电子密度沉淀颗粒主要成分为Ｃａ（２＋）。本研究直接证实心肌肌浆网Ｃａ（２＋）聚集能力障碍及线粒体Ｃａ（２＋）沉积增多是心肌缺血再灌注损伤的重要原因。

e observed the sequential alterations of calcium in situ within sarcoplasmic reticulum(SR)andmitochondria subcellular organelles in ischemic and reperfusional myocytes with Ca(2+) cytochemicalprobe(potassium pyroantimonate, PPA)combined with X-ray electron probe microanalysis, Calciumwas located mainly within sarcoplasmic reticulum, sarcolemma and nucleus. No calcium precipitates ex-isted in cytoplasm and mitochondria in normal myocardium. Thirty minutes after ischemia, a littleamount of Ca(2+) precipitates appeared within myocardial cytoplasm, rather than sarcoplasmic reticulumand sarcolemma, The calcium precipitates within sarcoplasmic reticulum and sarcolemma decreased sig-nificantly,while a large quantity of calcium precipitates appeared in cytoplasm and mitochondria until 30minutes after reperfusion. This situation became more prominent 60 minutes after reperfusion. Electronprobe microanalysis indicated that calcium was the major component of precipitates within myocytes.The study demonstrated directly that the overload of intraceIlular calcium during myocardial ischemiaand reperfusion was in subcellular level;